The difference between Hit-for-Miss and Hit-for-Pass

A few weeks ago, I wrote and post introducing the concept of Hit-for-Miss and I received a few questions about it because "Hit-for-Pass" is much more common on the interwebz, and it looks like it could do something similar, and I completely omitted it last time. What's up with that?

Let's embark on a short chronological journey explaining how HfM and HfP (as the cool kids call them) came to be, how they are different and why you should care.

Read More

12/4/20 11:15 AM
by Guillaume Quintard

Hit-for-Miss AND why a NULL TTL is bad for you

Varnish is a caching server, and a great one at that, that much we already know. But what about the content you don't want to cache? For example, those shopping cart requests and other completely uncacheable API calls?

We can of course handle it, but we've got to be wary of the sirens of the cargo cult because you will often see something like this on the internet:

sub vcl_backend_response {
# check if the backend response header named
# "cache-control" contains the word "private"
if (beresp.http.cache-control ~ "private") {
# if so, don't cache by limiting the Time-To-Live
# period to 0 second
set beresp.ttl = 0s;
}
}

This is both pretty intuitive, and also very wrong. In this post, we'll explore why it's a bad idea, how to do better, and along the way, we'll try to shine some light on a couple of lesser known features of Varnish.

Read More

10/15/20 4:12 PM
by Guillaume Quintard

How to set and override time to live (TTL)

If you’re familiar at all with Varnish, you know it improves content delivery performance by storing a copy of your content in cache, and every request thereafter is fulfilled by the cached content.

Read More

3/4/20 3:01 PM
by Arianna Aondio

Putting It All Together - Using Varnish Cache to Manage Dynamic CDN Content - Part 3

In the final installment of this series on managing dynamic CDN content, I will illustrate how Varnish Cache puts together the ideas of direct cache invalidation and TTL management to manage dynamic content. (Check out parts one and two of the series to get the whole story.)

Read More

2/9/16 12:00 PM
by Reza Naghibi

Varnish Software Blog

The Varnish blog is where our team writes about all things related to Varnish Cache and Varnish Software...or simply vents.

 

 
 

Posts by Topic

see all
 

SUBSCRIBE TO OUR BLOG